Production line(s) of automated tools are used to carry out the many steps typically required in the manufacture of microelectronic devices. A typical production line includes a series of tools set up within a fabrication facility. Processable substrates, e.g., in-process semiconductor wafers, are conveyed from tool to tool to carry out the desired sequence of process steps.
The production capacity of a fabrication facility is generally limited by the amount of useable manufacturing space in the fabrication facility. To increase production capacity, the size of the facility would have to be increased and/or the existing space would need to be used more efficiently. It is generally very capital intensive to build additional fabrication space. Thus, it is often more desirable to increase production capacity by using existing space more efficiently.
Tool footprint is one factor affecting how efficiently fabrication space is being used. Tool footprint refers to the area of floorspace used by a tool when it is set up. As between two tools that perform identical processes with the same throughput and comparable quality, the tool with the smaller footprint uses space more efficiently.
Tool throughput is another factor affecting how efficiently fabrication space is being used by a tool. For example, a tool occupying a certain amount of floorspace might be capable of processing a certain number of wafers in a given period of time, while a larger tool might be capable of processing a larger number of wafers in a given period of time. The larger tool might actually process a higher number of wafers per unit of time per unit of floorspace, making it more efficient to use in some instances. Thus, throughput and footprint often must be looked at together to assess how efficiently a tool uses fabrication floorspace.
Tools with reduced footprint and high throughput thus are desirable, as their use enhances production capacity per unit area of fabrication floorspace. Much research and development effort in the microelectronic industry is devoted to developing more space-efficient tools, and the demand for such tools remains strong.